Aquaphor RO-101 Full Set of Replacement Filters K5 K2 K7M RO Membrane K5 - Replacement filter for primary purification of water. Removes sediment particles such as sand and rust. Protects other stages of filtration. K2 - Replacement filter for deep purification of drinking water. Reduces all common impurities including chlorine, lead, bacteria and solid particles sized down to 3 micron. RO Membrane - Provides ultra-filtration of all contaminants including cysts, bacteria and viruses. It also removes water hardness from any initial level. K7M - Replacement cartridge for water conditioning and mineralization. Enriches water with minerals, which improves its taste and has a beneficial effect on health. Cartridges are easily replaced: push the button; twist off the old cartridge and twist on the new cartridge until you hear a click .